Scroll to see break-even price per barrel for oil in 2015 for select oil producers, and click on a country's name for more details. modest oil-price recovery and currency devaluations have lowered breakeven prices for countries like Russia and Nigeria, but some petrostates still need oil prices above $100 a barrel to balance their budgets.
There are dozens of types of gemstones â including diamonds, colored gemstones, and pearls â each with a unique set of physical and optical properties. GIRDLE â The narrow band around the perimeter of a polished or faceted diamond or colored gemstone.
Cutting andpolishingofgemstones There are two types ofwidelyused gem-stone cuts. Opaque or figured gemstonesare usually cut with a rounded upper sur-faceand a flat or rounded back.A stone cutting do not apply to all gemstones. Stones that are especially brittle, soft, or difficult to polishrequireadditional pro-cedures or specialtechniques.Manylapi-Fig.2. Variations of thecabochon cut.